Hi, another novice in need of help. I have bought some 24V Bulgin illuminated momentary switches MPI002 - see attachment and need them to illuminate when i press the button and turn off when I press the button again. I am not switching anything, just need the button to light up when I want. (I actually have 3 switches in a line, red, amber, green and ideally only one switch led can be illuminated at any one time, but this isnt too important, a like to have but not a necessity). Bulgin have told me what resisters to install, I just need a method of switching the led bit of the switch on and off.
Though a bit klunky (electromechanical), here is a push-on/push-off switching circuit I found some time back. Credit: **broken link removed**
He doesn't spell it out, but the relay coil voltage (12V) is 1/2 the supply voltage(24V), and R1, R2, and the coil resistances are all equal. I've used this with a 5V relay on a 12v supply.
Though a bit klunky (electromechanical), here is a push-on/push-off switching circuit I found some time back. Credit: **broken link removed**
He doesn't spell it out, but the relay coil voltage (12V) is 1/2 the supply voltage(24V), and R1, R2, and the coil resistances are all equal. I've used this with a 5V relay on a 12v supply.
That looks great, I think. Would anybody be kind enough to draw this onto a cricuit board with a parts list for me as I have no idea what the components are and how they go together (like the link on my original post as this was easy to follow).
Also, does anyone know approximatly how much it would be to buy all the bits. I have 50 switches.
Thanks for the fantastic quick responses, your all stars.
If you are going to impliment 50 of these, you should look at some version of Hero999's solid state toggle switch. 50 relays are not going to be cheap and is going to draw a lot of current...besides that drawn by the LEDs. For one, or maybe a couple, this is slick, but for a large array logic level flip-flops and transistor drivers would be much better.
Or, he could go to a 40174 quad-D FFs and get by with even less. The 4013 and 40174 can only source or sink about 2mA@12v per output, so he still might need to add drive transistor arrays and resistor SIPs. But, that's still a lot better than 50 of my relay circuits.
I have no idea what you both are talking about, but if its any help my PSU is 24V DC output and is 3Amp.
If using the items you are talking about means when I push one of the three buttons that button illuminates and the other buttons are inhibited and similarly if you then press one of the other buttons that button illuminates and the other goes out?. this would be the ideal situation (if its easy enough).
It has been suggested to me to use a repol unit, see attachment. What do you think?.
We were discussing the minutia of the one-button/one-LED toggle circuit.
I'm confused. What is it that you really want? 50 P-buttons/LEDs in groups of 3 or 50 groups of 3 P-buttons/LEDs, that only one of 3 will light...and do nothing else? The devil's in the details, and different solutions lend themselves to different spec's.
I'm not sure how the commercial programmable controlled fits into your request.
Most (all?) brands of CD4013's don't have Schmitt trigger clock inputs. Philips makes HEF4013, which does. The ones that don't, have maximum clock rise and fall times measured in microseconds. You need a Schmitt trigger in the clock line, or use an HEF4013.
All. I have 14Nr stainless steel plates, in each of these plates there are 3 illuminated switches, one red, one amber and one green. The three leds are a visual indication of the status of the room, green is room clean, amber is room needs cleaning, red is room in operation
So, the ideal situation is that only one illuminated switch can be on at any one time. This would have been a piece of cake if I had ordered latching switches, but being a numpty I ordered momentary switches and had the plates made to suit. I would simply change the switches but I cant find a latching illuminated switch the same size and as you can see from the photo it is a shame to change the flush appearance now.
As no-one seems to make a 24V bi-stable latching relay that works from a single impulse I am struggling to find the solution. To make things worse, I know absolutely bugger all about electronics (but I am learning fast)
I'm not sure how much LED drive you can get before you screw up the logic threshold, but it's only a few milliamps. I think you need LED drivers. You do need pulldown resistors on your diode OR gates, and 79L12 is a negative regulator. In your text, you had a 78L12, which is right.
A little too hasty throwing the schematic together. As I said I was uncomfortable with the LED on the outputs, so added some drivers...and the pull down resistors.